Ethanol metabolism and liver oxidative capacity in cold acclimation

Area of Science:

• Physiology
• Biochemistry
• Environmental Medicine

Background:

• Cold acclimation influences metabolic rate and cellular functions.
• Understanding the mechanisms behind enhanced energy expenditure in cold environments is crucial.

Purpose of the Study:

• To investigate the impact of cold acclimation on oxygen consumption and ethanol metabolism in rat liver.
• To elucidate the role of the sodium-potassium pump (Na++K+-activated adenosine-triphosphatase) in cold-induced metabolic changes.

Main Methods:

• Rats were exposed to 5°C for 4-6 weeks.
• Liver slices were used to measure oxygen consumption and ethanol oxidation rates.
• Enzyme activities (mitochondrial alpha-glycerophosphate oxidase, Na++K+-activated adenosine-triphosphatase) were assessed.
• In vivo ethanol disappearance rates were determined.
• Inhibitors (ouabain, dinitrophenol) were used to probe metabolic pathways.

Main Results:

• Cold exposure increased oxygen consumption by 30-80% and ethanol oxidation by 50%.
• Mitochondrial alpha-glycerophosphate oxidase and Na++K+-activated adenosine-triphosphatase activities significantly increased.
• Ouabain blocked the enhanced respiration and ethanol oxidation, while dinitrophenol was ineffective in cold-acclimated rats.
• In vivo ethanol metabolism accelerated despite reduced liver alcohol dehydrogenase activity.

Conclusions:

• Increased ATP hydrolysis by the sodium pump system is proposed as the driver for elevated oxygen consumption and ethanol metabolism in cold-acclimated rats.
• Cold acclimation alters liver function to enhance energy expenditure and metabolic processing.